Ultrasensitive NH3 Gas Sensor from Polyaniline Nanograin Enchased TiO2 Fibers

In this communication, we reported for the first time an ultrasensitive nanostructrued sensor that can detect 50 ppt of NH3 gas in air. Specifically, nanograins of a p-type conductive polymer, polyaniline (PANI), are enchased on an electrospun n-type semiconductive TiO2 fiber surface. The resistance of the p−n heterojunctions combining with the bulk resistance of PANI nanograins can function as electric current switches when NH3 gas is absorbed by PANI nanoparticles. As a result, the sensor sensitivity can be significantly improved. The sensor fabricated in this work is 1000 times more sensitive than the best PANI sensor reported in the literature.